Evidence for role of microRNA in Melanoma

Twitter is great for highlighting interesting journal articles, as I found when Edward Winstead from the NIH shared this paper from PLOSone on the importance of microRNA in melanoma in his Twitter stream (thanks, Ted!).

There has been a lot of interest in melanoma lately, with the rise of a couple of interesting new compounds targeting different mutations or kinases including CTLA4 by ipilimumab (BMS) and B-RAF by PLX-4032 (Plexxikon/Roche).

You can see some of the recent data I've blogged about here, here and here.

At the moment, we're waiting for the new data from PLX-4032 at a melanoma conference later this year and BMS may be filing their phase III data in ipilimumab by the end of this year after some promising reactions to the data presented last month in the plenary session at ASCO. In addition, GSK also have some compounds in earlier development that are generating interest.

How does the new data in PLOSone connect with melanoma?

Well, it's an aggressive and highly malignant cancer and scientists have long wondered how melanoma cells travel from primary tumours on the surface of the skin to the brain, liver and lungs, where they become more aggressive, resistant to therapy, and deadly. This ultimately makes treatment and control of the disease very challenging.

In Feb 2009, an article in PNAS (see reference below) suggested that the culprit might be a short strand of RNA called microRNA (miRNA) that is over-expressed in metastatic melanoma cell lines and tissues. It is also known that the Microphthalmia associated transcription factor (Mitf) is an important regulator in melanocyte development and has been shown to be involved in melanoma progression.
The new data reported in PLOSone this month takes our understanding a little further and shows that microRNAs are also involved in regulating Mitf in melanoma cells.

The authors concluded that:

"miR-148 and miR-137 present an additional level of regulating Mitf expression in melanocytes and melanoma cells. Loss of this regulation, either by mutations or by shortening of the 3′UTR sequence, is therefore a likely factor in melanoma formation and/or progression."

What this means is that the microRNA's involved may offer new therapeutic targets in order to either reduce the development of resistance or aggressive progression and metastasis (ie spread of melanoma) to other organs. In order words, future research may involve the addition of microRNA therapy to optimise outcomes.

For now, microRNA is very much a research on the rise but it won't be long before we start seeing the first RNA based therapies in the clinic based on a solid scientific research rationale. As our understanding of the complex biology improves, so does the chances of developing a multi-factorial strategy to combat the devastating disease.

For those of you interested in this exciting field, I'll cover a more basic primer on microRNA and RNA therapeutics in development in a future blog post.